Half-moon shaped machine

ABSTRACT

A crescent type gear machine comprises a spur gear in mesh with an internal gear in a housing and a stationary crescent shaped body between spur gear and the ring gear. The space between ring gear and the housing communicates with the high pressure area of the machine, a limited low pressure area being formed between crescent shaped body spur gear and ring gear. A ring having a meander shaped section to make it radially resilient encircles said ring gear. A depression area is provided on the inner surface of said resilient ring and engages part of the periphery of the gear ring to counteract the hydraulic forces thereon. Said depression area communicates with a depression area of smaller size between said resilient ring and the housing wall, the latter depression area being defined by resilient sealing means and communicates with the low pressure connection of the machine.

i United States Patent 1191 Molly I I 1 Sept. 18, 1973 HALF-MOON SHAPEDMACHINE [76] Inventor: Hans Molly, Dr. Eugen-Essig-Strasse 48, Malsch,Germany 22 fined; Nov. 22, 1971 211 A 1.N6.=21I1,o41; s2 U.S.Cl. 4s/17o, 41s/71 s11 lnt.Cl... F01c 1/10,F04c 1/06 [58] FieldofSenrch..41s/71,170'

56 References Cited UNITED sTATEs PATENTS FOREIGN PATENTS ORAPPLICATIONS 1,266,134 4/1968 Germany"; .;41s/71 2ll,7ll 10/1940Switzerland 418/170 Primary Examiner--Carlton R. Croyle AssistantExaminer-Michael Koczo, Jr. Attorney-Darbo, Robertson & Vandenburgh 57ABSTRACT A crescent type gear machine comprises a spur gear in mesh withan internal gear in a housing and a stationary crescent shaped bodybetween spur gear and the ring gear. The space between ring gear and thehousing communicates with the high pressure area of. the machine, alimited low pressure area being formed between crescent shaped body spurgear and ring gear. A

ring having a meander shaped section to make it radially resilientencircles said ring gear. A depression area is provided onthe innersurface of said resilient ring and engages part of the periphery of thegear ring to counteract the hydraulic forces thereon. Said depressionarea communicates with a depression area of smaller size between saidresilient ring and the housing wall, the latter depression area beingdefined by resilient sealing means and communicatesv with the lowpressure connection of the machine.

9 Claims, 2 m' sing'ngura PAIENIEUSEM 3,759,639

sum-1 or 2 INVENTOR. ffANs MaLLY PAIENIEDSEPIBIENS 3,759,639

SHEEY 2 0F 2 INVENTOR:

HANS MOLLY HALF-MOON SHAPED MACHINE This invention relates to ahydraulic pump or motor comprising a housing within which is a spur gearin mesh with a larger ring gear, and a stationary crescent shaped bodypositioned between the spur gear and the ring gear. The space betweenthe ring gear and the housing is in communication with the high-pressurerange of the machine and opens into a limited range of the suctionconnection defined between the half-moon shaped body, the hollow gearand the spur gear, and in which a depression field engages at theperiphery of the hollow gear for supporting the hollow gear otherwiserunning in the high-pressure space.

Machines of the type indicated in which the gear wheels aresubstantially operated in high-pressure and the suction space is limitedto a relatively small area, have the advantage-that the hydraulic forcesapplied to the gear wheels act in the sense of a seal of the suctionspace and tend to compress the parts. In known machines thehigh-pressure is limited to a narrow area and the gear wheels areoperated substantially in lowpressure, the high-pressure tends to forcethe gear wheels apart and to make the machine loose. For this reason,machines of the first-mentioned type can be operated at very highpressures. It has shown, that at such high pressures theproblem-ofdeformation of the ring gear is encountered due to theinfluence of the high bydraulic forces. I I

It is an object of this invention to counteract such a deformation ofthe ring gear.

According to the invention this object is attained by positioningbetween the ring gear and the housing wall, a bearing body which fitsaround the hollow gear with limited movement. The side of the bearingbody that is adjacent the hollow gear forms a cylindrical-bearingsurface and has a suction area. This suction area is in communicationwith a suction area of smaller size on the side of the housing on theoutside of the bearing body. This lattersuction area is defined byresilient V sealing means between the bearing body and the internalhousing wall and communicates with the suction connection.

In this manner, a relieving force is applied to the hollow gear by asuction area in the high-pressure space which force when correctlyarranged and dimensioned, counteracts the pressure forces which'tend todeform the hollow gear. The suction area on the bearing surface on theside of the hollow gear effects a drawing of the bearing body to thehollow gear, while the suction area on the side of the housing tends todraw the bearing body withthe hollow gear-towards the housing. Since thesuction area onthe side of the hollow gear has a greater size than thesuction area on the outside of the bearing body, it is ensured that thebearing body remains drawn to the hollow gear and cannot be withdrawnfrom. the bearing body by the opposing pressure of the pressure forcesand of the outer suction area. The resilient sealing means permit alimited movement of the bearing body relative to the housing. Moreover,in this manner the problem is solved of applying the suction area to abearing body attached to the hollow gear as by suction. On the otherhand, a free alignment of the bearing body to the hollow gear isensured.

The bearing body may be constituted by a radially'resilient ringsurrounding the hollow gear. By axially aligned indentations provided onthe ring extending alternately from one and then from the other side, ameander-shaped section is provided which is resilient in a pheripheraldirection, permitting a radial expansion and contraction of the ring.

The suction area on the side .of the housing can be defined by an O-ringeffecting, due to its elasticity, a seal on the one hand and on theother hand a limited movement of the bearing body.

If suction and pressure sides change in the machine for operationalreasons, the ring must have such opposing suction area arrangements onboth sides of the gear wheel centers, one of which communicates with onefluid pressure connection of the machine, and the other the gear wheelcenters, from these forces opposed components are produced in adirection of the connection line of the gear centers. The suction areasgear absorb the forces supporting due to the elasticity of the ring gearvia the teeth on the crescent, so that no wear can occur here. I

The direction of the force components to the center of the gear and anangle of rotation-position of this relieving area favorably influencingthe bending'line of this gear body results in a pivoting (illustrated inthe drawing) of the areas opposed relative to the center in a directiontowards the tooth engagement.

The suction area'arrange'ments serve to keep the ring gear free of thesupporting forces extending on the suction side through the end of theteeth towards the crescent, and moreover to so control the deformationof the same in the sealing range that a close contact of ring gear andspur gear extending across that range is obtained.

.An illustrative embodiment of this invention will hereinafter bedescribed more fully with reference to the accompanying drawings, inwhich:

FIG. 1 illustrates a section through a crescent'type hydraulic pumpormotor designed in accordance with this invention.

FIG. 2 is a perspective illustration of an annular bearing body used insuch a machine.

An internal ring gear 2 and a spur gear 3 are mounted in a housingl. Thering gear has a substantially greater diameter than the spur gear. Thecrescent shaped space between the ring gear and the spur gear is filledout by a crescent shaped body 4 stationary with respect to the housing.The spur gear 3 can be guided forlimited movement as by means of abearing 3a having loosene'ss at the top and-bottom with respect to theshaft 3b in a direction of the connection line of the gear wheel centersas indicated by arrow M and is otherwise supported in'the housing 1.Between the ring gear 2, the spur gear 3 and the crescent shaped body 4,a suction space 5 is defined which is in communication with a suctionconnection 6. The other part of the housing interior is underhigh-pressure and in communication with a high-pressure connection 7.

The internal diameter of the housing interior is substantially greaterthan the external diameter of the ring gear 2 so that an annular spaceis formed between the housing and the ring gear. An annular bearing body,8 is positioned in this annular space. As can best be seen from FIG. 2,the bearing body 8 has a section 9 which is resilient in a peripheraldirection. To this end, axially aligned slots 10, 11 extend inwardalternately from one side and then from the other side so that ameandershaped spatial configuration is obtained. By reason of thisresilient section 9, the bearing body 8 can expand and contract in aradial direction. On its inner face, the bearing body 8 has two opposedpressure area arrangements l2 and 13 respectively on the side of thehollow gear. Depending upon the use of the'machine one or the other ofthese areas serves as the suction area. They are identical except one isa left and the other is a right." Thus it is necessaryonly to discussthe arrangement 12. The pressure area arrangement 12 includes a areafield 14 on the inner face of the hollow gear bounded by a rectangularannular groove 15. The annular groovel is in communication with achannel 16. The channel 16 opens'into a suction area 18 which is definedbetween the ring 8 and the housing 1 by an O- ring 17. This outersuction area onthe side of the housing 1 is of smaller size than is thesuction area 1 4. It is in communication with the suction connection 6through a channel 19. Under the influence of the resilient section 9 agap initially exists between the hollow gear 2 and the ring 8. Dependingon the degree of pressure built up in the machine, the annular bearingbody 8 is compressed and the suction area 14 pulled against the ringgear 2. At the same time, the whole bearing body 8 is drawn against thehousing by the suction area 18. Thereby, a suction force is applied tothe ring gear 2 which counteracts the pressure forces which couldotherwise cause a deformation of the ring gear 2.

While the force components which would be vertical in FIG. 1, of theforces acting on the spur gear 3 and on the ring gear 2 substantiallycancel each other through the tooth engagement, the horizontal forcesare substantially absorbed by the suction area 18 so that ring gearabuts the housing only with a strongly reduced force on the right-handside in FIG. 1. The pressure area arrangements 12 and 13 respectivelyare offset downwardly (i.e. towards spur gear 3) relative to ring geardiameter which is at right angles theto the connection line of the gearwheel centers (the latter would be a vertical line in FIG. l Thisresults from the resolution of force with the spur gear 3 of limitedvertical movement relative to the housing.

The application of the suction forces to the ring gear 2 is accomplishedwith the invention in such a manner that the free abutment of the ringgear 2 to the crescent shaped body 4 is not impaired so that therefore atight operation of the machine is ensured. On the other hand, thepressure forces with which the ring gear 2 abuts the crescentshapedbody, is decreased to a wearreducing degree by the applied suctionforces.

By reason ofthe axially aligned slots 10 and 11 on the bearing body 8,the latter is resilient against the outer wall in an assembled state. Abacklash is produced between the ring gear and the bearing body 8 whichfloods the suction area arrangement 12 at low operating pressure.Nonetheless, the outer suction field 18 is operating as here no pressureexists. Thus, the gear wheel operates at low operating pressurewith'fully effective relief by the annular groove 15 with a tolerableleakage loss until the forces occurring here in the suction area arecapable to overcome the elasticity in section 9. With the herebyincreased initial pressure of the pump a highly tight operation of themachine occurs initially and is maintained up to the highest operatingpressures.

I claim:

1. In a gear machine comprising a housing, an internal ring gearrotatably mounted within the housing, a spur gear meshing with the ringgear, a stationary crescent-shaped body between the gears, said housinghaving a low pressure connection opening into a limited area definedbetween the body, the ring gear and the spur gear, and a high pressureconnection, means defining a high pressure field in juxtaposition to theright gear and defining a first low pressure field at the pe riphery ofthe ring gear," the improvement comprising:

said housing forming a rigid wall spaced from the periphery of the ringgear and defining an annular space between said wall and ring gear;

said means including a radially resilient annular hearing body in saidannular space and of a size to permit limited movement of the bodywithin the space between said wall and said ring gear periphery, saidfirst low pressure field being on the side of said body adjacent saidring gear periphery, said means defining a second low pressure fieldbetween the first low pressure field and the wall and on the side of thebody adjacent said wall, said second low pressure field being of smallerarea than said first low pressure field, said means including resilientsealing means between said wall and said body and surrounding saidsecond low pressure field, said second low pressure field communicatingwith said low pressure connection. I

2. in a machine as set forth in claim 1, wherein the bearing body has asection with slots therethrough from inside to outside, some of saidslots being part way across the body from one edge and other slots beingpart way across the body from the opposite edge to define ameander-shaped section on the body to provide said radial resiliency.

3. In a machine as set forth in claim 2, wherein said resilient means isan O-ring.

4. In a machine as set forth in claim 3, wherein said high pressurefield is on the side of said body adjacent said ring gear periphery andis referred to herein as the first high pressure field, said meansdefines a second high pressure field between the first high pressurefield and the wall and on the side of the body adjacent said wall, saidsecond high pressure field being of smaller area than said first highpressure field, said means in-' cluding resilient sealing means betweensaid wall and said body and surrounding said second high pressure field,said high pressure fields communicating with said high pressureconnection, said high and low pressure fields being on opposite sides ofa line connecting the centers of the gears.

5. in a machine as set forth in claim 4, including means guiding thespur gear for limited movement in the housing in the direction of saidline, said fields being offset with respect to that ring gear diameterwhich is at right angles to said line, said offset being in thedirection of the spur gear.

6. In a machine as set forth in claim 1, wherein said resilient means'isan O-ring.

7. In a machine as set forth in claim 1, wherein said high pressurefield is on the side of said body adjacent said ring gear periphery andis referred to herein as the first high pressure field, said meansdefines a second high pressure field between the first high pressurefield and the wall and on the side of the body adjacent saidt wall, saidsecond high pressure field being of smaller area than said first highpressure field, said means ineluding resilient sealing means betweensaid wall and said body and surrounding said second high pressure field,said high pressure field communicating with said high pressureconnection; said high and low pressure fields-being on diametricallyopposite sides of a line connecting the centers of the gears.

' 8. in a machine as set forth in claim 7, including means guiding thespur gear for limited movement in the body can expand in a radialdirection.

' i =o= n: =0:

-. mm STATES PATENT orrrer CERTIFICATE r @rrerron men, 7 3, 759,639Dated September 18, 1973 Inventofls) Hans Molly It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

In the abstract, line 2-, "internal gear" should be "internal ring gear"Col. 1, line 331 I should have a comma after "positioning" Col. 1, line46- I should have a comma after "which force" Col. 2, line 25 "Thesuction areas gear absorb" should be The suction areas on the ring gearabsorb" Col. 2, line 37 "end" should be "ends" Col. 3, line 18 "areafield 14 should be "suction area 14 Col. 3, line 45 insert "the" before"ring gear" Col. 3, line 45 delete "the" after "angles" Col. 4, line 14"right gear" should be "ring gear" Col. 6, line 11 insert "and contract"after "expand" Signed and sealed this 1st, day of oeeebermm,

(SEAL) e-et-Eest:

MCCOY M. GIBSON JR. or IT iARSE-ZALL DANN Arresting Officer Commissionerof Patents FORM PC4050 (10459) USCOMM-DC eoa'Ie-poo U,$. GOVERNMENTPRlNTHIG OFFICE I 9' 0-356-334,

1. In a gear machine comprising a housing, an internal ring gear rotatably mounted within the housing, a spur gear meshing with the ring gear, a stationary crescent-shaped body between the gears, said housing having a low pressure connection opening into a limited area defined between the body, the ring gear and the spur gear, and a high pressure connection, means defining a high pressure field in juxtaposition to the right gear and defining a first low pressure field at the periphery of the ring gear, the improvement comprising: said housing forming a rigid wall spaced from the periphery of the ring gear and defining an annular space between said wall and ring gear; said means including a radially resilient annular bearing body in said annular space and of a size to permit limited movement of the body within the space between said wall and said ring gear periphery, said first low pressure field being on the side of said body adjacent said ring gear periphery, said means defining a second low pressure field between the first low pressure field and the wall and on the side of the body adjacent said wall, said second low pressure field being of smaller area than said first low pressure field, said means including resilient sealing means between said wall and said body and surrounding said second low pressure field, said second low pressure field communicating with said low pressure connection.
 2. In a machine as set forth in claim 1, wherein the bearing body has a section with slots therethrough from inside to outside, some of said slots being part way across the body from one edge and other slots being part way across the body from the opposite edge to define a meander-shaped section on the body to provide said radial resiliency.
 3. In a machine as set forth in claim 2, wherein said resilient means is an O-ring.
 4. In a machine as set forth in claim 3, wherein said high pressure field is on the side of said body adjacent said ring gear periphery and is referred to herein as the first high pressure field, said means defines a second high pressure field between the first high pressure field and the wall and on the side of the body adjacent said wall, said second high pressure field being of smaller area than said first high pressure field, said means including resilient sealing means between said wall and said body and surrounding said second high pressure field, said high pressure fields communicating with said high pressure connection, said high and low pressure fields being on opposite sides of a line connecting the centers of the gears.
 5. In a machine as set forth in claim 4, including means guiding the spur gear for limited movement in the housing in the direction of said line, said fields being offset with respect to that ring gear diameter which is at right angles to said line, said offset being in the direction of the spur gear.
 6. In a machine as set forth in claim 1, wherein said resilient means is an O-ring.
 7. In a machine as set forth in claim 1, wherein said high pressure field is on the side of said body adjacent said ring gear periphery and is referred to herein as the first high pressure field, said means defines a second high pressure field between the first high pressure field and the wall and on the side of the body adjacent said wall, said second high pressure field being of smaller area than said first high pressure field, said means including resilient sealing means between said wall and said body and surrounding said second high pressure field, said high pressure field communicating with said high pressure connection, said high and low pressure fields being on diametrically opposite sides of a line connecting the centers of the gears.
 8. In a machine as set forth in claim 7, including means guiding the spur gear for limited movement in the housing in the direction of said line, said fields being offset with respect to that ring gear diameter which is at right angles to said line, said offset beIng in the direction of the spur gear.
 9. In a machine as set forth in claim 8, wherein said body is in the form of a ring and includes means for providing resiliency in a peripheral direction whereby the body can expand in a radial direction. 